Anti-pick cylinder lock



June 3, 1958 s. s. SCHILLIZZI 2,336,973

ANTI-PICK CYLINDER LOCK Filed Oct. 25, 1954 I N VEN TOR. 5191. v4 70/25 5. 50/11. 1. 172/ I I 5 BY ANTI-PICK CYLINDER LOCK Salvatore S. Schillizzi, New York, N. Y.

Application October 25, 1954, Serial No. 464,661 8 Claims. (Cl. 70-421 (Granted under Title 35, U. S. (lode (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes Without the payment of any royalties thereon or therefor.

This invention is described in an article published in Locksmith Ledger, September 1954, vol. XIV, number 9, pages 1 and 34. Locksmith Ledger is published by Locksmith Ledger, Inc., 505 Marlboro Road, Wood- Ridge, New Jersey.

This invention relates to a lock and more particularly to a pin tumbler cylinder lock for a locking mechanism which cylinder lock defies compromise by lock picking methods.

Commercially-traded pin tumbler cylinder locks generally include a cylindrical shell that is externally threaded for attachment to a lock mechanism. The shell is formed with a longitudinal eccentric bore. A key plug is rotatably mounted in the bore of the shell. The shell and the key plug are each formed with a row of transverse bores or sockets for receiving pin tumblers. The plug is formed with a longitudinal key slot in communication with the pin tumbler bores. A compression spring is disposed in each of the tumbler bores of the shell. A pair of pin tumblers are disposed in each pair of longitudinally aligned bores of shell and key plug. In each instance the pin tumbler which engages a compression spring is also known as a driver pin. The driver pins and the pin tumblers in abutment therewith are all of diiterent lengths to normally prevent the plug from rotating in the shell. A properly serrated key when inserted in the key slot of the plug raises the pairs of pin tumblers against the opposition of the compression springs to a level where their abutting ends are continuous with the periphery of the plug thereby permitting the plug to rotate in the shell. Generally, commerciallytraded pin tumbler cylinder locks require more than a A; revolution of the plug from the position where the pin tumbler bores in shell and key plug are aligned to move the cam on the end of the key plug enough to produce unlocking action.

The conventional pin tumbler cylinder lock described above can be readily picked by one skilled in this field. One common method for picking a locking mechanism controlled by a pin tumbler cylinder lock is to zip the pin tumblers through the key slot in the plug while at the same time constantly applying torque to the plug. Zipping is a method of causing all the tumbler pins in a cylinder lock to be raised by rapid in and out motion of athin picking tool in the key slot. The thin picking tool strikes the inner ends of the tumbler pins as it is moved in and out. The torque applied to the key plug causes the latter to rotate when the pin tumblers are moved into proper position by the picking tool.

There are commercially available pick-resistant pin tumbler cylinder locks but they difier structurally and functionally from this invention. One type of pick resistant cylinder lock available includes a mushroom type driver pin. Though it is somewhat more diificult to pick than conventional pin tumbler cylinder locks with a little more time rather than with any special training or tools, it may be picked. Additionally, a pick-resistant cylinder lock having a mushroom driver suffers the disadvantage that it can be forced it it is picked to the point where only the mushroom driver prevents rotation of the plug.

This invention is directed to an improved pin tumbler cylinder lock. It comprises conventional pin tumbler cylinder lock structure and in addition, comprises at least one auxiliary pin tumbler disposed in its shell and displaced angularly about A3 of a revolution to either side of the row of main pin turnblers. If the plug is turned without a proper key, an auxiliary pin tumbler is forced into a tumbler bore of the plug when it is moved into registration therewith. Each auxiliary pin tumbler is continuously biased toward the plug and is in a transverse plane in common with a pin tumbler bore in the plug. it jams the plug at a /a turn position.

The free end of each auxiliary pin tumbler of this invention is rounded. A springbiased locking pin, disposed in a longitudinal bore, engages the rounded end of each auxiliary pin tumbler. Each auxiliary pin tumbler is adapted to be forced part way into a corresponding pin tumbler bore in the plug by the spring-biased locking in and is adapted to be retained therein by the locking pin against all attempts at picking and pounding on the cylinder lock.

Normally a cylinder lock can be unscrewed and withdrawn from a locking mechanism when the pin tumbler bores in the plug are in alignment with the pin tumbler bores in the shell. Up to about A; revolution of the plug in either direction from this position this also holds true. Under those conditions, the cam at the end of the key plug would be within the cylindrical contour of the cylinder lock. Beyond revolution the cam would project beyond the contour of the cylinder lock and thereby would engage the wall of the locking mechanism to prevent withdrawal. This invention includes as a part of the cylinder look, a locking pin normally projecting beyond the contour of the cylinder lock to prevent withdrawal of the cylinder lock from the locking mechansim. The locking pin is retracted only when the plug is rotated to jammed position of the plug.

From the practical point of View, this invention is adapted to utilize commercial pin tumblers and commercial driver springs as auxiliary pin tumblers and spring-biased locking pins, respectively.

An object of this invention is to provide an improved lock.

A further object is to provide an improved pin tumbler cylinder lock which defies compromise by lock-picking methods.

A further object is to provide an improved pin tumbler cylinder lock which jams locked pursuant to attempted lock-picking.

A further object is to provide a pin tumbler cylinder lock which affords a positive indication of an unsuccessful lock-picking attempt.

A further object is to provide a cylinder lock adapted to resist unauthorized operation even if picked.

A further object is to provide an improved pin tumbler cylinder lock which jams locked pursuant to attempted lock-picking and which cannot be unjammed by any additional lock-picking efforts.

A further object is to provide an improved pin tumbler cylinder lock which jams pursuant to attempted lockpicking and which cannot be removed bodily from its locking mechanism until either picked or rotated by a key to jammed position.

A further object is to provide an improved pin tumbler cylinder lock which resists removal from its locking mechanism.

A further object is to providean improved pin tumbler cylinder lock which defies compromise by lock-picking methods and which is adaptable for mastering without any sacrifice of'security.

Other objects and many of the attendant advantages of this invention will be readily appreciated asthe same becomes better understood by reference to'the following detailed description when considered in connection with the accompanying drawing wherein:

Fig. 1 isa longitudinalsection with a part shownin elevationof a preferred embodiment of this invention,

Fig. 2 is an end elevation of the look ,as seen from thele'it o f'Fig. 1,

Fig. 3fis a longitudinal section taken along the line 33 of Fig. 2 withparts shown in elevation,

Fig. 4 is a transverse section taken along the line '4-.4

of Fig. 3 with; parts shown in elevation, and

'Fig. 5 is an isometric View partly broken away of the cylinder lock shown in jammed condition and with some details omitted for clarity. V

The embodiment of the invention shown in the drawings comprises a shell 12 formed with a longitudinal bore 14 eccentric to the axis of the shell 12. Mounted for rotation in the bore 14 of the shell 12 is a key plug 16 formed with a key slot 18. The shell 12 and the key plug 16 are each formed with a longitudinal row of pin tumbler bores 22 and 24. The pin tumbler bores 22 are aligned with the respective pin tumbler bores 24 in the normal position of the key plug 16 in the shell 12. Tumbler pins 26 and 28 are disposed for reciprocation in tumbler bores 22 and 24 in the shell and keg plug, respectively. The pin tumblers 28 are also known as driver pins. A compression coil spring 32 is disposed in each of the pin tumbler bores 22 in the shell for engaging each of the driver pins 28, respectively. A key 34 which is properly serrated is used for positioning the pin tumblers 26 so. that they terminate at the periphery of the key plug 16. Through the use of a properly serrated key, the key plug 16 may be rotated. However, experts in this field may rotate key plug 16 to open the associated locking mechanism by resort to lock picking as described previously.

Some conventional portions of pin tumbler cylinder locks not essential to acomplete description of this embodiment of the invention are omitted for purposes of clarity. For'example, the screw threads on the shell for fastening the cylinder lock to a locking mechanism, a longitudinal slot in the outer surface of the shell for cooperation with a set screw, a cam at the end of the key plug opposite the key receiving end whereby movement of the key plug is transferred to locking or latching mechanism, are not illustrated since they are details not directly concerned with this invention. Below is described the improvements in a conventional pin tumbler cylinder lock for precluding successful lock picking.

Pairs of auxiliary pin tumbler bores 36 and 38, respectively, are formed in the shell 12 to the sides of the row of main tumbler bores 22 and extend radially of the axis of longitudinal bore 14 from the outside of the shell 12 to the longitudinal bore 14. The auxiliary pin tumbler bores 36. and 38 are angularly displaced from the row of main tumbler bores 22 approximately revolution of the key plug 16. Though this is a preferred design, it is not intended in the limiting sense. Each of the auxiliary tumbler bores 36 and 38 are disposed in a transverse plane in common with a pin tumbler bore 22. On the drawing (Fig. 3), they are shown in planes common to the second and fourth main pin tumbler bores, respectively. This is not intended in the limiting sense since other combinations are possible. If the key plug 16 is rotated counterclockwise, A; revolution from the position shown in Fig. 4, the pair of auxiliary pin tumbler bores '36 are aligned with corresponding pin 4 tumbler bores in the key plug. The diameter of each of the auxiliary tumbler bores 36 and 38 is the same as the diameter of the main pin tumbler bores. Auxiliary pin tumblers 42 and 44 are disposed in the auxiliary tumbler bores 36 and 38. The ends of the auxiliary pin tumblers 42 and 44 remote from the ends abutting the key plug 16 are rounded. Standard pin tumblers available commercially preferably are used as auxiliary pin tumblers 42 and 44. I

The shell 12 is further formed with longitudinal locking-pin bores (Fig. 3) 46 and 48 which are coplanar with and intersect the auxiliary tumbler bores 36, as shown; two additional longitudinal locking pin bores 46 and 48, not shown, are coplanar with and intersect the auxiliary tumbler bores 33 in substantially the same manner as the bores t6 and 48 shown in Fig. 3. Locking pins 52 and 54 preferably standard pin tumblers available commercially are disposed in the locking-pin bores46 and.

48. Each of the locking pins has rounded inward ends for abutment with the rounded ends of the auxiliary pin tumblers 42 and '44. Compression coil springs 56 and 58 preferably stifier than those used for the main pin tumblers are disposed behind the locking pins forcing the rounded ends of the latter into engagement with the rounded ends of the auxiliary tumbler pins. If either set of the auxiliary pin tumblers 42 or 44 moves inwardly out of the path of its associated set of locking pins 52 and 54, the locking pins extend across therespective auxiliary pin tumbler bores for a considerable portion of their length, thereby blocking the auxiliary tumbler bores and thereby preventing the auxiliary pin tumblers from again moving outwardly. It is important for purposes,

of this invention that locking pins 52 and 54 be able'to extend completely across the auxiliary bores 36 and 38. This is explained below in connection with ensuring against picking the cylinder out of jammed condition.

If the key plug is rotated by means other than a properly serrated key 34 positioned in the key slot of the key plug for positioning the pin tumblers 26 so that they terminate at the periphery of the key plug, one of the sets of the auxiliary pin tumblers 42 or 44 will be projected part way into tumbler bores 24 in thekey plug. Therefore, the plug is jammed in the shell when itis rotated /8 revolution from normal position Without a key 34.

This action occurs because the coil springs 56 and 58- are constantly forcing the locking pins 52 and 54 forwardly against the auxiliary pin tumblers 42 and 4450 that their rounded ends are in abutment. tumbler bores in the key plug 12 are brought into alignment with one set of the auxiliary tumbler bores the associated spring-biased locking pins 52 and 54 force the auxiliary tumbler pins inwardly part way into tumbler bores in the key plug jamming the key plug and the locking pins 52 and 54 project completely across'the auxiliary tumbler bores blocking the return path ofthe'auxiliary tumbler pins. Because one set of the locking pins extends completely across one set of the auxiliary pin tumbler bores after an attempt is made to pick the lock, it is virtually impossible to unjam the cylinder while work ing from theoutside of a door. Known attempts by experts are to date unsuccessful. If picks are positioned against the jammed pin tumblers and a mallet is used to pound the front end of the lock, the lock is not unjammed springs 56 and 58 exert suflicientforce, it is virtually impossible .to drive the locking pins back sufliciently to When the pin force the auxiliary tumbler pins outwardly with picks. Repeated experiments with a cutaway lock according to this invention have shown that even while viewing the inner workings of the lock it cannot be picked out of jammed condition. Evidence of attempted picking is indicated by the position of the jammed plug.

If a series of locks according to this invention were conventionally modified for mastering by one key there would be no lessening of the security afforded by the auxiliary pin tumblers and their spring-biased locking PIES.

An additional expedient sometimes resorted to as a method for unauthorized unlocking of cylinder locks has been to loosen the set screw which normally prevents unscrewing of the cylinder lock. The set screw is loosened while the door is open and free access is had to the locking mechanism. This permits anyone to unscrew the pin tumbler cylinder lock out of the locking mechanism and out of the door at any time and permits the locking mechanism to be opened with one finger. The loosening of the set screw can be accomplished unobtrusively during normal business hours. After normal business hours when everyone has left, the pin tumbler cylinder lock is unscrewed and the locking mechanism is opened with one finger. This invention includes means for preventing removal of the pin tumbler cylinder lock from its mounting except when the key plug is rotated /8 rotation with a key or to jammed position by lock picking. For this purpose the shell 12 is further formed with a radial bore 62. A pin 64 having an enlarged head 66 is disposed in bore 62 and slidably engages the wall of the bore 62. A bushing 72 is secured at the outer end of bore 62. A compression coil spring 68 is positioned around pin 64 and is compressed between the head 66 of pin 64 and bushing 72. The end of the key plug 16 is formed into the shape of a cam for permitting the pin 64 to be completely retracted only when the key plug 16 is rotated Vs revolution out of normally locked position. In other words, the pin tumbler cylinder lock according to this invention cannot be unscrewed for removal from the locking mechanism when the key plug pin tumbler bores are aligned with the shell pin tumbler bores. It must be rotated /s revolution. T 0 remove the cylinder lock from the locking mechanism without the use of a key it must be picked even if the cylinder lock set screw, conventionally included in a locking mechanism is threaded out of engagement with the cylinder look.

In operation a properly serrated key 34 is used to unlock a locking mechanism controlled by a cylinder lock according to this invention in the same manner as a key is used to unlock any conventional, commercially traded pin tumbler cylinder lock. However, if there is an attempt to unlock the locking mechanism by picking it, the cylinder lock key plug will be caused to jam in /8 rotated position either clockwise or counterclockwise from the normal position of the key plug. Auxiliary pin tumblers, functioning as deadlocking pins, are forced into corresponding tumbler bores in the key plug jamming it against any further rotation clockwise or counterclockwise. This ofiers positive indication of attempted lock-picking. Locking pins project across the auxiliary tumbler bores for the purpose of defeating further lockpicking attempts, i. e. through the use of a pick applied to the jamming pin tumblers and a mallet pounding the front end of the cylinder lock. The cylinder lock cannot be withdrawn from the locking mechanism though the cylinder lock set screw may have been loosened; this is due to the action of the pin 64. Pin 64 is completely retracted for permitting removal of the cylinder lock from its locking mechanism only when the key plug is rotated /s revolution from normal position' To open a closure secured by a lock jammed in this manner it is necessary to drill the cylinder lock.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically describe-d.

1 claim:

1. A pin tumbler cylinder lock comprising; a shell; a key plug mounted for rotation in said shell; a row of main pin tumblers mounted in said shell and said key plug for normally locking said key plug against rotation in said shell, said main pin tumblers adapted to be so oriented in said shell and said key plug through the use of a properly serrated key to unlock said key plug for permitting rotation of said key plug in said shell; at least one auxiliary pin tumbler mounted in said shell to each side of said row of main pin tumblers for coaction with said key plug and adapted to jam said key plug against rotation in either direction of rotation pursuant to a lockpicking attempt; said auxiliary pin tumblers being inactive to jam said key plug when key plug rotation is caused by a properly serrated key; a locking pin for each auxiliary pin tumbler, said locking pins mounted in said shell and abutting one end of said auxiliary pin tumblers, said locking pins and said auxiliary pin tumblers formed at their abutting ends with rounded portions; and springbiasing means for said auxiliary locking pins mounted in said shell to constantly urge said auxiliary pin tumblers to jamming engagement with said key plug.

2. A pin tumbler cylinder lock comprising; a shell formed with 'a row of main tumbler bo es; a key plug rotatably mounted in said shell and formed with a row of tumbler bores adapted for alignment with the row of main tumbler bores in said shell when said key plug is in locked position; said key plug further formed with a key slot in communication with its row of tumbler bores; main pin tumblers and biasing means therefor mounted in the tumbler bores of said shell and said key plug and normally operative for locking said key plug against rotation out of its locked position; said shell further formed with two pairs of auxiliary radial tumbler bores, the two pairs being angularly spaced in opposite directions from the main tumbler bores about /8 turn about the axis of rotation of said key plug; corresponding ones of the two pairs of auxiliary tumbler bores being in transverse alignment with one of the main tumbler -bores in said shell; an auxiliary pin tumbler in each auxiliary pin tumbler bore in abutment with said key plug and formed to provide a rounded end portion directed away from said key plug; said shell further formed with a plurality of longitudinal bores, one for each of the auxiliary pin tumbler bores and intersecting at substantially a right angle the corresponding auxiliary pin tumbler bores; a locking pin mounted in each longitudinal bore and formed with a rounded end portion in abutment with the rounded end portion of a corresponding auxiliary pin tumbler; a compression spring in each longitudinal bore for projecting each locking pin firmly into engagement with the corresponding auxiliary pin tumbler; whereby when said key plug is caused to rotate with the aid of a properly serrated key, said auxiliary pin tumbler and said corresponding locking pins remain inactive but when said key plug is caused to rotate out of locked position pursuant to a lock-picking attempt, at least one auxiliary pin tumbler is projected partway into a tumbler bore "in said key plug jamming said key plug /8 turn away from locked position against further rotation in either direction and whereby the locking pin associated with the lastmentioned auxiliary pin tumbler is projected across the associated auxiliary pin tumbler bore -for preventing the last-mentioned auxiliary pin tumbler from moving radially outward out of jamming position relative to said key plug.

3. A pin tumbler cylinder lock comprising; a shell formed with a main tumbler bore; a key plug rotatably mounted in said shell and formed with a tumbler bore adapted for alignment with the main tumbler bore in said shell when said key plug is in locked position; said key plug further formed with a key slot in communication with its tumbler bore; a main pin tumbler and biasing means therefor mounted in the tumbler bore of said shell and said key plug and normally operative for locking said key plug against rotation out of its locked position; said shell further formed with an auxiliary tumbler bore spaced from the main tumbler bore about /5 turn about the axis of rotation of said key plug and in transverse alignment with the main tumbler bore in said shell; an auxiliary'pin tumbler in the auxiliary pin tumbler bore in abutment with said key plug and formed to provide a rounded end portion directed away from said key plug; said shell further formed with a longitudinal bore intersecting at substantially a right angle, the auxiliary pin tumbler bore; a locking pin mounted in the longitudinal bore and terminating in a rounded end portion in abutment with the rounded end portion of said auxiliary pin tumbler; and a compression spring in the longitudinal bore for forcing said locking pin firmly into engagement with the auxiliary pin tumbler.

4. A pin tumbler cylinder lock comprising; a shell; a key plug mounted for rotation in said shell; a row of main pin tumblers mounted in said shell and said key plug for normally locking said key plug against rotation'in said shell, said main pin tumblers adaptedrto be so oriented in said shell and said key plug through the use of a properly serrated key to unlock said key plug for permitting rotation of said key plug in said shell; an auxiliary pin tumbler mounted in said shell to one side of said row of main pin tumblers for coaction with said key plug and adapted to jam said key plug against rotation pursuant to a lock-picking attempt; said auxiliary pin tumbler, being inactive to jam said key plug when key plug rotation is caused by a properly serrated key; a locking pin for said auxiliary pin tumbler, said locking pin mounted in said shell and abutting one end of said auxiliary. pin tumbler, said locking pin and said auxiliary pin tumbler formed at their abutting ends with rounded portions; and springbiasing means for said locking pin mounted in said: shell to constantly urge said auxiliary pin tumbler to jamming engagement with said key plug.

5. in a pin tumbler cylinder lock, a shell formed with pin tumbler bores, a key plug formed with pin tumbler bores adapted for alignment with the pin tumbler bores in said shell, said key plug mounted for rotation insaid shell, key controllable locking pin tumblers in the pin tumbler bores formed in saidshell and said key plug, respective'ly, key plug jamming means 'slidable in said shell towards said key plug, and biased means slidable in said shell transversely to said jamming means and continuously pressing against said jamming means and adapted for forcing said key plug jamming means part way into at least one pin tumbler bore in said key plug and also adapted for projecting into the path of said jamming means to prevent withdrawal of said jamming means from said key plug to jam said key plug against. any further rotation pursuant to a lock-picking attempt, the abutting surface portions of said keyplug jamming means and said biased means, respectively, being inclined to provide for camming action, said key plug adapted for rotation in said shell free of interference from said jamming means through the useof a properly serrated key.

6. In a pintumbler cylinder lock of the type having a shell formed wtih a row of pin tumbler bores anda key plug rotatable in said shell and formed with a key slot and with, a row of pin tumbler bores, in communication with said key slot, the pin tumbler bores in said key plug being in registration with the pin tumbler bores in said shell in one rotary position of said key plug relative to said shell, pin tumblers backed by compression springs in the bores of said shell and pin tumblers in the bores of said key plug, whereby when said respective rows of, pin tumbler bores are in registration said pin tumblers in said shell project into said key pluglocking said key plug against rotation and when a properly serrated key is inserted intothekey slot the key raises said pin tumblers to free said key plug for rotation in said shell; the improvements in said lock which include said. shell being formed with a jamming pin bore extending to said key plug and spaced; transversely. from one bore of said row of bores in said shell whereby when said key plug is rotated a small fraction of a revolution in that direction from. its position Where the respective rows of bores are in registration, said jamming pin bore is in registrationwith one of the boresin said key. plug, a jamming pin in said jamming pin bore, said shell formed with another bore transverse to said jamming pin bore and extending across said jamming pin bore, biased means in said other bore abutting one end of said jam.- ming pin when the latter bears against the surface of said key plug, theabutting endportions of said jamming pin and said biasedmeans being mutually inclined to provide for camming action whereby said biased means 'continuously presses. said jamming pin against said key plug and when said key plug is rotated without a properly serrated key in the key slot to the rotary position where said jamming pin is in line with one of the rowof bores in said key plug said biased means forces said jamming pin into the aligned bore in said key plug and said biased means projects across the return path of said jamming pin to prevent withdrawal of said jamming pin from said key plug.

7. The pin. tumbler cylinder lock recited in claim 5 wherein said shell further has an additional jamming pin bore and jamming pin therein,.tr ansverse bore and biased means therein and located to the side of said rowof pin tumbler bores in said shell opposite to the corresponding structure recited in claim 5 andin substantially the same relationship and for the same purpose as the corresponding structure recited in claim 8. The pin tumbler cylinder lock as defined in clairn-6 wherein each jamming pin is substantially identical-to a pin tumbler and each said biased means includes a pin that is substantially identical to a pin tumbler.

References Cited in the file of this patent UNITED STATES PATENTS OConnell Nov. 22, 1938 

